something that has confused me with coroutines is that you o

Question

something that has confused me with coroutines is that you often see things done with runBlocking Doesn t that sort of defeat the purpose of making a thing a suspend function

Andy Gibel · Answer

For instance if you are on the main thread and calling into a viewModel to load from DB in a suspend function using the runBlocking builder is that not equivalent to just calling the blocking version without using coroutines at all

bezrukov · Answer

Just don t do that as much as possible It was designed for the cases when you need to perform blocking operation

bezrukov · Answer

From docs gt This function should not be used from a coroutine It is designed to bridge regular blocking code to libraries that are written in suspending style to be used in main functions and in tests

Andy Gibel · Answer

I guess this goes back before coroutines to the argument that db INSERTs are fast enough for main thread

Andy Gibel · Answer

most Room Coroutine examples I see do this

jw · Answer

Those are wrong then

Andy Gibel · Answer

thumbsup Good to know Trying to form a True North for coroutine usage Seems to be lots of incorrect stuff out there

bezrukov · Answer

Could you show these examples Inserts may take a while if there is another transaction for example

Andy Gibel · Answer

Is it true then that correct usage of coroutine Mvvm will most certainly make use of an async vehicle like LiveData or RxJava or Flow

Andy Gibel · Answer

``` fun getAllSprockets List lt Sprockets gt = runBlocking val deferred Deferred lt List lt Sprockets gt gt = async repository getAllSprockets deferred await ``` consider something like this as a public viewmodel interface

Andy Gibel · Answer

from what I m hearing this is flat wrong

Andy Gibel · Answer

which jives with my other opinion that having `getters` on a VM is an antipattern

bezrukov · Answer

wrapping repository call to async and then to runBlocking doesn t make any sense to me shrug it could be ```suspend fun getAllSprockets = repository getAllSprockets ``` if repository call is suspend fun or ```fun getAllSprockets = repository getAllSprockets ``` if it blocking or ```suspend fun getAllSprockets = runBlocking return repository getAllSprockets ``` if repository call is suspend fun but you need blocking

Andy Gibel · Answer

OK cool so it s not just me thinking this is weird slightly smiling face In the first case you are exposing a suspend function to the consumer of the VM which I suppose is just moving the problem Eventually I guess you d want to use a launch or async builder to wrap that

Andy Gibel · Answer

for anyone following this thread I found this very useful <https proandroiddev com how to make sense of kotlin coroutines b666c7151b93> Best thing I ve read yet to make sense of things